1. Field of the Invention
This invention relates to a marine fender fixed and projecting laterally from a berthing base such as quay wall and the like.
2. Related Art Statement
It is known that a marine fender such as a hollow cylindrical fender, a hollow truncated fender, a hollow pyramid fender and the like, all of which being made from rubber or rubbery elastomeric material, is arranged in a protruding arrangement onto the berthing base such as quay wall or the like.
A marine fender 1 shown in FIG. 4 is one of these fenders. This fender 1 is fixed in a lateral posture to a quay wall 2 and comprises a fender body 3 of a thick hollow cylindrical shape made of rubber, a rigid wall member (ring plate) 4 attached to the head portion of the fender body 3, a steel frame member 5 threaded onto the wall member 4, and a shock receiving plate 6 made of a synthetic resin and arranged along the surface of the steel frame member 5.
The marine fender 1 generally has a deformation characteristic as shown by a strain-reaction force curve a in FIG. 6. Since the reaction force of the marine fender 1 is large at an initial compression state as seen from the curve a, the marine fender 1 has drawbacks that the hull of the vessel is apt to be damaged and the pitching and rolling movement of the mooring vessel is made large.
Further, since the marine fender 1 is provided at its head portion with the steel frame member 5, if the hull of the vessel is not flat, a local concentration of loading is apt to be caused, resulting in the damaging of the hull.
A well-known rubber marine fender 7 shown in FIG. 5 is provided at its head portion with a foamed body 8 of a flexible resin embedded therein, so that it has a deformation characteristic as shown by a curve b in FIG. 6 owing to the presence of the foamed body 8. Thus, this rubber fender 7 eliminates the above mentioned problems inherent in the fender 1. Further, since the weight of the head portion is lighter than that of the fender 1, it is not required to use a chain 9 for supporting the weight of the head portion as used in the fender illustrated in FIG. 3.
In the rubber marine fender 7 of FIG. 5, however, the rubber body should be vulcanized together with the foamed body 8 embedded therein, so that the production is technically difficult because the foamed body 8 is weak when subjected to high-temperature heating. In order to solve this problem, it may be considered that the head portion including the foamed body 8 is joined to the fender body through an adhesive. In the latter case, the head portion is peeled off from the fender body at the joint face because the marine fender is generally subjected to a large deformation amounting to 50% deformation, so that the use of the adhesive can not be adopted.
When the foamed body 8 is damaged by frictionally contacting the head portion of the rubber fender 7 with the hull of the vessel to break the head portion, the broken rubber fender 7 should be replaced with a new one as a whole, which becomes disadvantageous economically.